A method and device for analyzing stress state of a fabricated bridge pier

Abstract

This invention provides a method and apparatus for stress state analysis of prefabricated bridge piers. The method includes: determining a stress concentration function based on a finite element model of prestressed threaded steel bars in the prefabricated bridge pier; detecting cracks in the prestressed threaded steel bars in their initial state to determine a crack distribution probability function; constructing a global finite element model of the prefabricated bridge pier and identifying target crack elements within the global finite element model; determining a corrected stiffness for each target crack element based on the stress concentration function, the crack distribution probability function, and the global finite element model; assigning the corrected stiffness to the corresponding target crack element and repeating the above steps until the obtained corrected stiffness converges, and using the calculated stress of the global finite element model at this point as the stress distribution of the prefabricated bridge pier. This invention, based on the simulation of stress concentration in threaded steel bars, can accurately reconstruct the stress state of prefabricated bridge piers, improving the safety of subsequent construction.

Description

Technical Field

[0001] This invention relates to the field of bridge stress design and analysis technology, and in particular to a method and apparatus for stress state analysis of prefabricated bridge piers. Background Technology

[0002] Bridge piers and abutments are the main structural components that bear the vertical and horizontal loads transmitted from the superstructure. Precast assembly technology, which involves prefabricating the piers in sections or as a whole in a factory and then assembling them on-site, significantly reduces on-site work time, minimizes environmental constraints, ensures construction quality, and reduces environmental impact. For precast structures, the assembly and connection technology between components is crucial to the entire precast structural system. A systematic study of the key technologies of the vertical prestressed system for prefabricated piers and abutments is needed to develop scientific and rigorous key technologies for the design and construction of precast prestressed systems for bridge piers that can guide practical engineering applications. This will provide a basis for the design, manufacturing, installation, construction, and inspection of prestressed systems for piers and abutments, and provide a solid technical guarantee for the design and application of precast prestressed systems for piers and abutments. However, when performing stress analysis on precast prestressed piers and abutments using finite element analysis tools, the connecting threads of the prestressed joints are too small to be modeled effectively, while simulation through contact between elements cannot express the stress concentration state of the connecting threads, making the stress analysis results less realistic. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and device for stress state analysis of prefabricated bridge piers, so as to improve the accuracy of stress state analysis and calculation of prefabricated bridge piers in finite element calculation by simulating the stress concentration state of threaded steel bars, thereby improving the safety of subsequent construction.

[0004] To address the aforementioned technical problems, embodiments of the present invention provide a method for stress state analysis of prefabricated bridge piers, comprising:

[0005] Based on the finite element model of prestressed threaded steel bars in prefabricated bridge piers, a stress concentration function is determined. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bar under load and the crack size on the prestressed threaded steel bar.

[0006] Crack detection is performed on the prestressed threaded steel bars in the initial state to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state;

[0007] Construct an overall finite element model of the prefabricated bridge pier and determine the target crack element in the overall finite element model;

[0008] Based on the stress concentration function, the crack distribution probability function, and the overall finite element model, the corrected stiffness of each target crack element is determined.

[0009] The modified stiffness is assigned to the target crack element, and the above steps for determining the modified stiffness of each target crack element are repeated until the new round of modified stiffness converges. The calculated stress of the overall finite element model when the modified stiffness converges is used as the stress distribution of the prefabricated bridge pier.

[0010] In one embodiment, based on the finite element model of prestressed threaded steel bars in prefabricated bridge piers, the stress concentration function is determined, including:

[0011] Obtain the dimensional data of the prestressed threaded steel bar, and construct the finite element model of the steel bar based on the dimensional data; the finite element model of the steel bar contains at least one crack region;

[0012] The finite element model of the steel reinforcement is loaded based on a preset load and a preset crack size to obtain the simulated stress concentration factor corresponding to the preset load and the preset crack size;

[0013] The preset crack size, the simulated stress concentration factor, and the preset load are fitted to obtain the stress concentration function.

[0014] In one embodiment, the stress concentration function is expressed by the following equation:

[0015]

[0016] in, The stress concentration factor in the stress concentration function is represented by ; A and B both represent fitting parameters; w represents the crack length parameter in the stress concentration function; d represents the crack depth parameter in the stress concentration function. This indicates the yield strength of the prestressed threaded steel bar; This indicates the stress at the crack.

[0017] In one embodiment, crack detection is performed on prestressed threaded steel bars in their initial state to determine the crack distribution probability function of the prestressed threaded steel bars in their initial state, including:

[0018] Obtain an axially partially cut sample of the prestressed threaded steel bar, and determine the initial number and initial crack length at the root of the thread in the axially partially cut sample.

[0019] The initial number of cracks and the initial crack length are fitted based on a preset Weibull distribution to obtain the crack distribution probability function.

[0020] In one embodiment, the crack distribution probability function is expressed by the following equation:

[0021]

[0022] in, δ represents the cumulative probability that the initial crack length is less than a; a represents the crack length parameter in the crack distribution probability function; δ represents the scale parameter of the preset Weibull distribution; λ represents the shape parameter of the preset Weibull distribution.

[0023] In one embodiment, the modified stiffness of each target crack element is determined based on the stress concentration function, the crack distribution probability function, and the overall finite element model, including:

[0024] Based on the crack distribution probability function, the calculated crack length corresponding to each target crack element is determined;

[0025] The overall finite element model is loaded to obtain the calculated stress of the prefabricated bridge pier at each target crack element;

[0026] Based on the stress concentration function, the calculated stress of the prefabricated bridge pier at each target crack element, and the calculated crack length corresponding to each target crack element, the corrected stiffness of the prefabricated bridge pier at each target crack element is determined.

[0027] In one embodiment, determining the calculated crack length corresponding to each target crack element based on the crack distribution probability function includes:

[0028] Determine the random cumulative probability of each target crack element;

[0029] Based on the crack distribution probability function and the random cumulative probability, the calculated crack length of each target crack element is determined;

[0030] The target crack element whose calculated crack length is less than the preset crack length is determined as a non-crack element.

[0031] In one embodiment, based on the stress concentration function, the calculated stress of the prefabricated bridge pier at each target crack element, and the calculated crack length corresponding to each target crack element, the corrected stiffness of the prefabricated bridge pier at each target crack element is determined, including:

[0032] Based on the crack depth threshold, the stress concentration function, the calculated stress, and the calculated crack length, the calculated stress concentration factor for each target crack element is determined.

[0033] Based on the calculated stress concentration factor and the initial stiffness value of the corresponding target crack element, the corrected stiffness at each target crack element is determined.

[0034] In one embodiment, the convergence of the new round of stiffness correction is determined in response to the difference between the new round of stiffness correction and the previous round of stiffness correction being less than a preset difference value.

[0035] Embodiments of the present invention also provide a prefabricated bridge pier stress state analysis device, comprising:

[0036] The first fitting module is used to determine the stress concentration function based on the finite element model of the prestressed threaded steel bars in the prefabricated bridge pier. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bars under load and the crack size on the prestressed threaded steel bars.

[0037] The second fitting module is used to detect cracks in the prestressed threaded steel bars in the initial state in order to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state.

[0038] The crack determination module is used to construct the overall finite element model of the prefabricated bridge pier and determine the target crack elements in the overall finite element model.

[0039] The stiffness correction module is used to determine the corrected stiffness of each target crack element based on the stress concentration function, the crack distribution probability function, and the overall finite element model.

[0040] The loop module is used to assign the corrected stiffness to the corresponding target crack element and repeat the above steps of determining the corrected stiffness of each target crack element until the new round of corrected stiffness converges, and use the calculated stress of the overall finite element model when the corrected stiffness converges as the stress distribution of the prefabricated bridge pier.

[0041] The above-described solution of the present invention has at least the following beneficial effects:

[0042] (1) The present invention fits the stress concentration function that characterizes the stress concentration factor and the crack size on the threaded steel bar, and introduces the stress concentration function into the calculation of the overall finite element model of the pier, so as to accurately capture the stress distribution of the threaded steel bar at the crack in the subsequent overall structural analysis of the pier, and ensure the accuracy of the overall stress analysis of the pier.

[0043] (2) The present invention detects cracks in the threaded steel bar sample and fits a crack distribution probability function that characterizes the relationship between the number of cracks and the crack length distribution. Subsequently, the crack distribution probability function is introduced into the stress analysis of the overall structure, making the analysis closer to the actual engineering and improving the realism of the overall finite element model calculation.

[0044] (3) The present invention corrects the stiffness of the crack element and performs iterative calculations to make the mechanical behavior of the crack closer to the actual stress state, thereby realizing a more accurate restoration of the stress state of the prefabricated bridge pier in the finite element calculation, making the stress calculation results more accurate and improving the safety of subsequent construction.

[0045] It should be understood that the implementation of any embodiment of the present invention does not mean that it will simultaneously possess or achieve multiple or all of the above-mentioned beneficial effects. Attached Figure Description

[0046] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0047] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0048] Figure 1 This is a flowchart illustrating the stress state analysis method for prefabricated bridge piers provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the structural form of a prefabricated bridge pier provided in an optional embodiment of the present invention;

[0050] Figure 3 This is a schematic diagram of a finite element model of reinforcing steel provided in an optional embodiment of the present invention;

[0051] Figure 4 This is a stress concentration function fitting graph provided in an optional embodiment of the present invention;

[0052] Figure 5 This is a sampling schematic diagram provided in an optional embodiment of the present invention;

[0053] Figure 6 This is an image observed under a microscope according to an optional embodiment of the present invention;

[0054] Figure 7 This is a schematic diagram of the crack distribution probability function fitting provided in an optional embodiment of the present invention;

[0055] Figure 8This is a schematic diagram of the overall finite element model provided in an optional embodiment of the present invention;

[0056] Figure 9 This is a schematic diagram of the calculated stress distribution results provided by an optional embodiment of the present invention;

[0057] Figure 10 yes Figure 9 A sectional view;

[0058] Figure 11 This is a schematic block diagram of the prefabricated bridge pier stress state analysis device provided in an embodiment of the present invention;

[0059] Figure 12 This is a schematic block diagram of an electronic device provided in an embodiment of the present invention; and

[0060] Figure 13 This is a schematic block diagram of a computing device provided in an embodiment of the present invention. Detailed Implementation

[0061] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0062] It should be understood that the terms "comprising / including," "consisting of," or any other variations are intended to cover non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements includes not only those elements but may also include, where necessary, other elements not expressly listed, or elements inherent to such a product, apparatus, process, or method. Without further limitation, an element defined by the phrases "comprising / including," "consisting of," does not exclude the presence of additional identical elements in the product, apparatus, process, or method that includes said element.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0064] like Figure 2As shown, the prefabricated bridge pier 1 in the following embodiments of the present invention is assembled from different segments, such as pier base 10, first segment 11, second segment 12, third segment 13, and fourth segment. Prestressed threaded steel bars 2 are provided between different connecting segments, and the prestressed threaded steel bars 2 extend from the top to the bottom of the prefabricated bridge pier 1 to generate tension in the prefabricated bridge pier 1. Because the number of prestressed threaded steel bars 2 in the prefabricated bridge pier 1 is large and their size is small, they are not suitable for modeling. Simulating the stress concentration state of the prestressed threaded steel bars 2 through the contact between different segments cannot accurately express the stress concentration state of the prestressed threaded steel bars 2.

[0065] Based on this, such as Figure 1 As shown, an embodiment of the present invention proposes a method for stress state analysis of prefabricated bridge piers, which may include the following steps:

[0066] Step 11: Based on the finite element model of the prestressed threaded steel bars in the prefabricated bridge pier, determine the stress concentration function. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bars under load and the crack size on the prestressed threaded steel bars.

[0067] Step 12: Crack detection is performed on the prestressed threaded steel bars in the initial state to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state.

[0068] Step 13: Construct the overall finite element model of the prefabricated bridge pier and determine the target crack element in the overall finite element model;

[0069] Step 14: Based on the stress concentration function, crack distribution probability function, and overall finite element model, determine the corrected stiffness of each target crack element;

[0070] Step 15: Assign the corrected stiffness to the corresponding target crack element and repeat the above steps to determine the corrected stiffness of each target crack element until the new round of corrected stiffness converges. Then, use the calculated stress of the overall finite element model when the corrected stiffness converges as the stress distribution of the prefabricated bridge pier.

[0071] In this embodiment, the stress concentration of the prestressed threaded steel bar 2 is first analyzed. By constructing a finite element model of the steel bar and loading it, a stress concentration function characterizing the stress concentration factor and crack size is fitted. Here, the influence of the geometric features of the cracks on the prestressed threaded steel bar on its stress distribution is quantified into a specific functional relationship and introduced into the stress analysis and calculation of the subsequent overall model to improve the accuracy of the subsequent stress analysis.

[0072] For prestressed threaded steel bars, the high-strength cold-rolled steel bars undergo a thread extrusion process during which metal accumulates at the root of the thread, inevitably resulting in defects at the thread root. This causes severe stress concentration at the defective area, inevitably weakening the strength of the steel bar. These cracks are generally distributed at the thread root. By performing crack detection on prestressed threaded steel bars in their initial state (after steel bar fabrication and before application to bridge piers), a crack distribution probability function is generated. This function characterizes the relationship between the number of cracks and the crack length. In subsequent analysis, the crack distribution probability function can be used to characterize the probability of cracks that prestressed threaded steel bars may carry in their initial state, thus avoiding the neglect of the initial thread state of the steel bars in traditional analysis methods and improving the accuracy of subsequent analysis.

[0073] When performing stress analysis on the bridge piers, it is necessary to construct an overall finite element model of the prefabricated bridge pier 1. The overall finite element model is as follows: Figure 8 As shown, the specific construction process of the overall finite element model is consistent with that of the steel reinforcement finite element model, and will not be repeated here. In order to simulate the stress concentration phenomenon at the root of the prestressed threaded steel bar 2, the element corresponding to the root of the thread needs to be marked as a crack element in the overall finite element model (in actual engineering applications, cracks generally exist at the root of the thread on the prestressed threaded steel bar). During the loading calculation stage of the overall finite element model, the stiffness of the corresponding crack element can be corrected by the stress and crack length at the crack element. Since the stiffness of the crack element depends on the stress at the crack, and the stress at the crack depends on the stiffness distribution, it is necessary to perform stress calculation based on the corrected stiffness, and perform an iterative calculation process of stiffness correction based on the calculated stress, so that the mechanical behavior of the crack gradually approaches the real state. After multiple rounds of calculation and the corrected stiffness converges, the stress distribution calculated by the overall finite element model at this time can be used as a more accurate stress distribution of the prefabricated bridge pier.

[0074] In the above embodiments, by introducing stress concentration functions, probabilistic crack distribution, and iterative stiffness correction, the crack effect in the initial state of the prestressed threaded steel bars at the connection part of the prefabricated bridge pier can be quantified and introduced into the overall structural analysis of the bridge pier, thereby improving the accuracy and reliability of the stress analysis of the overall finite element model and thus improving the safety of subsequent construction.

[0075] In an optional embodiment of the present invention, the confirmation condition for the convergence of the new round of stiffness correction in step 15 above is:

[0076] Step 151: In response to the fact that the difference between the new round of stiffness correction and the previous round of stiffness correction is less than the preset value of the difference, it is determined that the new round of stiffness correction has converged.

[0077] In this embodiment, when the difference between the new round of corrected stiffness and the previous round of corrected stiffness is less than the preset difference value, it indicates that the stiffness of the crack element has basically stabilized and no longer changes with the number of iterations. Correspondingly, the stress distribution of the bridge pier calculated by the overall finite element model also tends to stabilize. Here, the preset difference value can be set based on engineering experience.

[0078] It should be understood that, since there may be multiple cracks on prestressed threaded steel bars, when calculating the corrected stiffness of the target crack element, it is necessary to pre-set a number of target crack elements whose corrected stiffness meets the convergence condition (that is, the proportion of the number of target crack elements whose corrected stiffness meets the convergence condition to the total number of target crack elements reaches a certain threshold, such as 80%), in order to ensure that the stress distribution of the overall finite element model reaches a stable state, thereby ensuring the accuracy and reliability of subsequent stress analysis and calculation based on the overall finite element model.

[0079] In an optional embodiment of the present invention, step 11 above may include:

[0080] Step 111: Obtain the dimensional data of the prestressed threaded steel bar and construct a finite element model of the steel bar based on the dimensional data; the finite element model of the steel bar contains at least one crack region;

[0081] Step 112: Load the finite element model of the steel reinforcement based on the preset load and preset crack size to obtain the simulated stress concentration factor corresponding to the preset load and preset crack size;

[0082] Step 113: Fit the preset crack size, simulated stress concentration factor and preset load to obtain the stress concentration function.

[0083] In this embodiment, it is necessary to first obtain the dimensional data of the prestressed threaded steel bars in the prefabricated bridge pier to construct a finite element model of the steel bars. The constructed finite element model of the steel bars is as follows: Figure 3 As shown, it contains at least one crack region 21. Specifically, a 200mm length of PSB1080 grade steel bar from the clamping end of the prestressed threaded steel bar can be used to create a three-dimensional solid model. The thread height is 3mm, the thread spacing is 20mm, and the thread base width is 12mm. Cracks of different preset sizes, such as different preset depths d and different preset lengths w, are set in the crack region 21 at the root of the steel bar thread. Parametric analysis is then performed on the finite element model of the steel bar. For example, the crack depth can be set to 0.5mm, 0.6mm, 0.8mm, and 1mm, and the crack arc length (i.e., crack length) can be set to 1 / 2 circumference, 1 / 8 circumference, 1 / 4 circumference, 1 / 2 circumference, 3 / 4 circumference, and full circumference, respectively. The crack chamfer radius is 0.5mm. The stress concentration factors at the tips of cracks of different sizes under different preset loads are calculated using the finite element model of the steel bar. The corresponding preset length, preset depth, simulated stress concentration factor, and preset load are fitted to obtain the stress concentration function.

[0084] Here, when setting cracks of different preset sizes, it is necessary to first adjust the size of the crack region to obtain a sufficient number of data sets corresponding to "crack length-crack depth-stress concentration factor" in order to avoid overfitting and improve the generalization performance of the fitting function.

[0085] In an optional embodiment of the present invention, the stress concentration function described above can be expressed by the following formula:

[0086]

[0087] in, denoted by , where A and B represent the stress concentration factor in the stress concentration function; both A and B represent fitting parameters; w represents the crack length parameter in the stress concentration function; and d represents the crack depth parameter in the stress concentration function. This indicates the yield strength of prestressed threaded steel bars; This indicates the stress at the crack.

[0088] In this embodiment, finite element analysis shows that the stress concentration factor of the prestressed threaded steel bar has a certain relationship with the crack depth d and crack arc length w. Considering the influence of stress and yield strength at the crack, the aforementioned stress concentration function is finally formed. The fitting parameters A and B can be obtained by least squares fitting, and the fitting diagram is shown below. Figure 4 (In the figure, the X-axis represents d / w, the Y-axis represents y, and the Z-axis represents...) For example, the fitted value of fitting parameter A can be 1.5, and the fitted value of fitting parameter B can be 1.3. As can be seen from the figure, the sum of squared errors of the stress concentration function SSE = 0.05, and the coefficient of determination R0... 2 =0.99, indicating that the selected finite element model for the reinforcing steel has a good fit and the prediction results are good.

[0089] In an optional embodiment of the present invention, step 12 above may include:

[0090] Step 121: Obtain an axially partially cut sample of the prestressed threaded steel bar, and determine the initial number and length of the initial cracks at the root of the thread in the axially partially cut sample.

[0091] Step 122: Fit the initial number of cracks and the initial crack length based on the preset Weibull distribution to obtain the crack distribution probability function.

[0092] See Figure 5 and Figure 6Samples of prestressed threaded steel bars were cut, and the number and length of cracks at the root of the thread in the axially cut samples were observed under a microscope. The microscopic images of the cracks and the rib roots marked ① to ⑧ are shown below. Figure 6 As shown, load loading tests were conducted simultaneously. The test results showed that the failure location of the axially locally cut sample was always located at the root of the thread. After the load loading test, the initial crack length was measured and statistically analyzed using a 100x microscope. Since the crack length of cold-rolled steel bars exhibits significant dispersion, statistical analysis can be used to process the initial crack length to obtain an initial crack length with a certain confidence level. It is assumed that the cumulative distribution function of the initial crack length in the initial state follows a preset Weibull distribution, and the number of initial cracks and the initial crack length are fitted based on the preset Weibull distribution. The fitting results are shown below. Figure 7 As shown.

[0093] In this embodiment, based on microscopic observation and pre-set Weibull distribution fitting, the uncertainty of local cracks in the threaded steel bars is introduced into the overall pier structure analysis in a probabilistic form, avoiding the deviation caused by artificially assuming crack parameters, so that the model is more in line with the actual project, thereby improving the accuracy and reliability of subsequent stress analysis.

[0094] In an optional embodiment of the present invention, the above-mentioned crack distribution probability function can be expressed by the following formula:

[0095]

[0096] in, δ represents the cumulative probability that the initial crack length is less than a; a represents the crack length parameter in the crack distribution probability function; δ represents the scale parameter of the preset Weibull distribution; λ represents the shape parameter of the preset Weibull distribution.

[0097] In an optional embodiment of the present invention, step 14 above may include:

[0098] Step 141: Based on the crack distribution probability function, determine the calculated crack length corresponding to each target crack element.

[0099] Specifically, step 141 above may include:

[0100] Step 1411: Determine the random cumulative probability of each target crack element;

[0101] Step 1412: Determine the calculated crack length for each target crack element based on the crack distribution probability function and the random cumulative probability.

[0102] In this embodiment, a random number in the range [0,1] can be generated for each target crack element based on a random function, and the random number can be used as the random cumulative probability of the corresponding target crack element. The random cumulative probability can be input into the crack distribution probability function to calculate the calculated crack length corresponding to each target crack element.

[0103] Here, the crack length is generated by random sampling, so that the crack length distribution conforms to the statistical regularity observed in actual operation. At the same time, the randomness of the crack is incorporated into the subsequent stress analysis calculation, avoiding the bias caused by subjective assumptions, and thus ensuring the accuracy of the subsequent stress analysis.

[0104] In an optional embodiment of the present invention, step 141 above may further include:

[0105] Step 1413: Determine the target crack element whose calculated crack length is less than the preset crack length as a non-crack element.

[0106] Since the random number corresponding to the random cumulative probability of each target crack element is uniform, the calculated crack length obtained will strictly follow the Weibull distribution. That is, a considerable number of target crack elements will have very small calculated crack lengths. At this time, the actual impact of target crack elements with small calculated crack lengths on the stiffness degradation of this local area can be ignored.

[0107] Reverting target crack elements with calculated crack lengths less than a preset crack length to non-crack elements essentially involves setting a filtering threshold. This retains cracks that have a real impact on the stiffness and stress distribution of the bridge pier structure, while ignoring microcracks that are physically and computationally negligible. This approach maintains the crack length distribution characteristics while improving computational efficiency and ensuring convergence stability, resulting in analysis results that more closely reflect actual engineering conditions. Here, the preset crack length can be set based on engineering experience.

[0108] In an optional embodiment of the present invention, step 14 above may include:

[0109] Step 142: Load the overall finite element model to obtain the calculated stress of the prefabricated bridge pier at each target crack element. Refer to the corresponding calculation results. Figure 9 and Figure 10 ;

[0110] Step 143: Based on the stress concentration function, the calculated stress of the prefabricated bridge pier at each target crack element, and the calculated crack length corresponding to each target crack element, determine the corrected stiffness of the prefabricated bridge pier at each target crack element.

[0111] In this embodiment, after marking and determining multiple target crack elements in the overall finite element model, loading calculations (such as prestressing tension and external loads) are performed, and the calculated stress at each target crack element is extracted. This calculated stress is the stress level of the crack region under the current overall stiffness distribution, and it is also used as one of the input parameters for subsequent stiffness correction calculations.

[0112] Furthermore, in an optional embodiment of the present invention, step 143 may include:

[0113] Step 1431: Based on the crack depth threshold, stress concentration function, calculated stress, and calculated crack length, determine the calculated stress concentration factor for each target crack element;

[0114] Step 1432: Based on the calculated stress concentration factor and the initial stiffness value of the corresponding target crack element, determine the corrected stiffness at each target crack element.

[0115] In this embodiment, the crack depth parameter d in the stress concentration function can be fixed as the crack depth threshold, and the calculated stress and corresponding calculated crack length of the target crack element can be input into the stress concentration function for calculation to obtain the calculated stress concentration coefficient of each target crack element; further, the initial stiffness of the target crack element is divided by the calculated stress concentration coefficient to obtain the corrected stiffness.

[0116] In a feasible example, when the prestress is 1080 MPa and the stress amplitude Δσ = 50 MPa, even if the entire cross-section of the threaded steel bar enters the yield stage, as long as the initial crack depth is less than 0.2 mm, the crack propagation fatigue life of the threaded steel bar can still be guaranteed to be more than 1 million cycles. Therefore, the manufacturing defect depth of the threaded steel bar is reduced to below 0.2 mm. At this time, when calculating under the most unfavorable working condition, that is, taking the crack depth threshold as 0.2 mm, the stress concentration factor is calculated. In order to characterize the effect of stress concentration, the most obvious effect of stress concentration in reality is the increase in strain at the stress concentration point. Therefore, the embodiment of this application performs stiffness correction by stiffness conversion, thereby simulating the strain change.

[0117] The stress state analysis method provided by the above embodiments of the present invention simulates the stress concentration state of prestressed threaded steel bars and introduces stress concentration functions, crack distribution probability functions, and stiffness iteration corrections to quantify the crack effect on the threaded steel bars at the connection of prefabricated bridge piers and introduce it into the stress analysis of the overall structure of the bridge pier. This allows for a more accurate reconstruction of the stress state of the prefabricated bridge pier in finite element calculations, thereby improving the accuracy, reliability, and engineering applicability of the finite element calculation results, and ultimately enhancing the safety of subsequent construction.

[0118] It should be understood that the stress state analysis method provided in the above embodiments is not limited to prefabricated bridge piers. It also has reference and promotion value for other engineering fields with micro-threaded structures and overall structural analysis needs. Furthermore, the specific process of the stress state analysis method provided in the above embodiments can be stored in a processor and iteratively stored and calculated based on deep learning algorithms to increase automatic logical calculation and judgment, and strengthen the automatic output of the final stress distribution, so as to realize the automatic analysis of the stress state of prefabricated bridge piers.

[0119] like Figure 11 As shown, an embodiment of the present invention also provides a prefabricated bridge pier stress state analysis device 30, comprising:

[0120] The first fitting module 31 is used to determine the stress concentration function based on the finite element model of the prestressed threaded steel bars in the prefabricated bridge pier. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bars under load and the crack size on the prestressed threaded steel bars.

[0121] The second fitting module 32 is used to perform crack detection on the prestressed threaded steel bars in the initial state in order to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state.

[0122] Crack determination module 33 is used to construct the overall finite element model of the bridge pier and determine the target crack element in the overall finite element model.

[0123] The stiffness correction module 34 is used to determine the corrected stiffness of each target crack element based on the stress concentration function, crack distribution probability function and the overall finite element model.

[0124] The loop module 35 is used to assign the corrected stiffness to the corresponding target crack element and repeat the above steps of determining the corrected stiffness of each target crack element until the new round of corrected stiffness converges, and use the calculated stress of the overall finite element model when the corrected stiffness converges as the stress distribution of the prefabricated bridge pier.

[0125] It should be noted that this device is the same as the above-mentioned prefabricated bridge pier stress state analysis method. All implementation methods in the above-mentioned method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0126] like Figure 12As shown, embodiments of the present invention also provide an electronic device 50, comprising: a memory 51 for storing one or more computer programs; and one or more processors 52 for executing the one or more computer programs. When the computer programs are run by the processors, they execute the aforementioned method for analyzing the stress state of prefabricated bridge piers. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects. The electronic device 50 is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device 50 can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown in this invention, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the invention described and / or claimed herein.

[0127] like Figure 13 As shown, electronic device 50 is a computing device or computer system, which may include CPU 501 (computing unit), which can perform various appropriate actions and processes according to a computer program stored in ROM 502 (read-only memory) or a computer program loaded from storage unit 508 into random access RAM 503 (memory). RAM 503 may also store various programs and data required for the operation of electronic device 50. CPU 501, ROM 502, and RAM 503 are interconnected via bus 504. I / O interface 505 (input / output interface) is also connected to bus 504.

[0128] Multiple components in electronic device 50 are connected to I / O interface 505, including: input unit 506, such as keyboard, mouse, etc.; output unit 507, such as various types of displays, speakers, etc.; storage unit 508, such as disk, optical disk, etc.; and communication unit 509, such as network card, modem, wireless transceiver, etc. Communication unit 509 allows electronic device 50 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0129] CPU 501 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of CPU 501 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. CPU 501 performs the various methods and processes described above. For example, in some embodiments, the prefabricated pier stress state analysis method can be implemented as a computer software program tangibly contained in a computer-readable storage medium, such as storage unit 508. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 50 via ROM 502 and / or communication unit 509. When the computer program is loaded into RAM 503 and executed by CPU 501, one or more steps of the prefabricated pier stress state analysis method described above can be performed. Alternatively, in other embodiments, CPU 501 can be configured to perform the prefabricated pier stress state analysis method by any other suitable means (e.g., by means of firmware).

[0130] Embodiments of the present invention also provide a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the methods described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0131] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0132] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0133] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0134] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0135] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0136] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0137] Furthermore, it should be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent solutions of the present invention. Moreover, the steps performing the above series of processes can naturally be executed in the order described, but are not necessarily required to be executed in chronological order; some steps can be executed in parallel or independently of each other. Those skilled in the art will understand that all or any step or component of the method and apparatus of the present invention can be implemented in any computing device (including processors, storage media, etc.) or network of computing devices, in hardware, firmware, software, or a combination thereof. This is something that those skilled in the art can achieve by using their basic programming skills after reading the description of the present invention.

[0138] Therefore, the object of the present invention can also be achieved by running a program or a set of programs on any computing device. The computing device can be a known general-purpose device. Therefore, the object of the present invention can also be achieved simply by providing a program product containing program code for implementing the method or apparatus. That is, such a program product also constitutes the present invention, and the storage medium storing such a program product also constitutes the present invention. Obviously, the storage medium can be any known storage medium or any storage medium developed in the future. It should also be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent to the present invention. Furthermore, the steps for performing the above series of processes can naturally be performed in the order described, but are not necessarily required to be performed in chronological order. Some steps can be performed in parallel or independently of each other.

[0139] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for stress state analysis of prefabricated bridge piers, characterized in that, include: Based on the finite element model of prestressed threaded steel bars in prefabricated bridge piers, a stress concentration function is determined. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bar under load and the crack size on the prestressed threaded steel bar. Crack detection is performed on the prestressed threaded steel bars in the initial state to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state; Construct an overall finite element model of the prefabricated bridge pier and determine the target crack element in the overall finite element model; Based on the stress concentration function, the crack distribution probability function, and the overall finite element model, the corrected stiffness of each target crack element is determined. The modified stiffness is assigned to the target crack element, and the above steps for determining the modified stiffness of each target crack element are repeated until the new round of modified stiffness converges. The calculated stress of the overall finite element model when the modified stiffness converges is used as the stress distribution of the prefabricated bridge pier.

2. The method for stress state analysis of prefabricated bridge piers according to claim 1, characterized in that, Based on the finite element model of prestressed threaded steel bars in prefabricated bridge piers, the stress concentration function is determined, including: Obtain the dimensional data of the prestressed threaded steel bar, and construct the finite element model of the steel bar based on the dimensional data; the finite element model of the steel bar contains at least one crack region; The finite element model of the steel reinforcement is loaded based on a preset load and a preset crack size to obtain the simulated stress concentration factor corresponding to the preset load and the preset crack size; The preset crack size, the simulated stress concentration factor, and the preset load are fitted to obtain the stress concentration function.

3. The method for stress state analysis of prefabricated bridge piers according to claim 2, characterized in that, The stress concentration function is expressed by the following formula: ； in, The stress concentration factor in the stress concentration function is represented by ; A and B both represent fitting parameters; w represents the crack length parameter in the stress concentration function; d represents the crack depth parameter in the stress concentration function. This indicates the yield strength of the prestressed threaded steel bar; This indicates the stress at the crack.

4. The method for stress state analysis of prefabricated bridge piers according to claim 1, characterized in that, Crack detection is performed on prestressed threaded steel bars in their initial state to determine the crack distribution probability function of the prestressed threaded steel bars in their initial state, including: Obtain an axially partially cut sample of the prestressed threaded steel bar, and determine the initial number and initial crack length at the root of the thread in the axially partially cut sample. The initial number of cracks and the initial crack length are fitted based on a preset Weibull distribution to obtain the crack distribution probability function.

5. The method for stress state analysis of prefabricated bridge piers according to claim 4, characterized in that, The crack probability distribution function is expressed by the following formula: ； in, δ represents the cumulative probability that the initial crack length is less than a; a represents the crack length parameter in the crack distribution probability function; δ represents the scale parameter of the preset Weibull distribution; λ represents the shape parameter of the preset Weibull distribution.

6. The method for stress state analysis of prefabricated bridge piers according to claim 1, characterized in that, Based on the stress concentration function, the crack distribution probability function, and the overall finite element model, the corrected stiffness of each target crack element is determined, including: Based on the crack distribution probability function, the calculated crack length corresponding to each target crack element is determined; The overall finite element model is loaded to obtain the calculated stress of the prefabricated bridge pier at each target crack element; Based on the stress concentration function, the calculated stress of the prefabricated bridge pier at each target crack element, and the calculated crack length corresponding to each target crack element, the corrected stiffness of the prefabricated bridge pier at each target crack element is determined.

7. The method for stress state analysis of prefabricated bridge piers according to claim 6, characterized in that, Based on the crack distribution probability function, the calculated crack length corresponding to each target crack element is determined, including: Determine the random cumulative probability of each target crack element; Based on the crack distribution probability function and the random cumulative probability, the calculated crack length of each target crack element is determined; The target crack element whose calculated crack length is less than the preset crack length is determined as a non-crack element.

8. The method for stress state analysis of prefabricated bridge piers according to claim 6, characterized in that, Based on the stress concentration function, the calculated stress of the prefabricated bridge pier at each target crack element, and the calculated crack length corresponding to each target crack element, the corrected stiffness of the prefabricated bridge pier at each target crack element is determined, including: Based on the crack depth threshold, the stress concentration function, the calculated stress, and the calculated crack length, the calculated stress concentration factor for each target crack element is determined. Based on the calculated stress concentration factor and the initial stiffness value of the corresponding target crack element, the corrected stiffness at each target crack element is determined.

9. The method for stress state analysis of prefabricated bridge piers according to claim 1, characterized in that, In response to the fact that the difference between the new round of stiffness correction and the previous round of stiffness correction is less than a preset difference value, it is determined that the new round of stiffness correction has converged.

10. A prefabricated bridge pier stress state analysis device, characterized in that, include: The first fitting module is used to determine the stress concentration function based on the finite element model of the prestressed threaded steel bars in the prefabricated bridge pier. The stress concentration function is used to characterize the relationship between the stress concentration factor of the prestressed threaded steel bars under load and the crack size on the prestressed threaded steel bars. The second fitting module is used to detect cracks in the prestressed threaded steel bars in the initial state in order to determine the crack distribution probability function of the prestressed threaded steel bars in the initial state. The crack determination module constructs the overall finite element model of the prefabricated bridge pier and determines the target crack elements in the overall finite element model. The stiffness correction module is used to determine the corrected stiffness of each target crack element based on the stress concentration function, the crack distribution probability function, and the overall finite element model. The loop module is used to assign the corrected stiffness to the corresponding target crack element and repeat the above steps of determining the corrected stiffness of each target crack element until the new round of corrected stiffness converges, and use the calculated stress of the overall finite element model when the corrected stiffness converges as the stress distribution of the prefabricated bridge pier.

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